1. Field
The present application relates to a motor.
2. Background
Generally, an Electronic Power Steering (EPS) System is a device for securing steering stability of a vehicle, and functions to provide a torque in a steering direction of a driver using a motor and thus to allow easy handling. Unlike an existing hydraulic power steering (HPS) system, the EPS system can control an operation of the motor according to driving conditions, and thus can enhance steering performance and steering feeling.
In the EPS system, an electronic control unit (ECU) drives the motor according to the driving conditions detected by a vehicle speed sensor, a torque angle sensor, a torque sensor, and the like, secures turning stability, provides rapid resilience, and thus enables a driver to safely drive a vehicle. The motor used in the EPS system has a cylindrical shape, and an exterior thereof is formed by a housing of which an upper portion is opened and a bracket coupled to the upper portion of the housing, and a stator is disposed in the housing.
A rotator rotated according to an electromagnetic interaction with the stator is disposed at a center of the stator. The rotor is rotatably supported by a rotational shaft. A vehicle steering shaft is connected to an upper portion of the rotational shaft to provide power to assist a steering operation.
The motor generates vibration and noise at a high frequency area, and this phenomenon is associated with a resonant frequency. Therefore, there is a need to shift or improve the resonant frequency, thereby reducing the vibration and the noise. A material of the housing may be changed from iron to aluminum, or a thickness of the housing may be adjusted. However, there is a problem in that material costs and manufacturing costs are increased.